This invention is related generally to liquid purification and, more particularly, to separation of impurities from drinking water by distillation.
Reasonably-pure drinking water is an absolute necessity of life and clean, fresh-tasting drinking water is one of its pleasures. Most persons in well-developed countries like the United States have access to safe, reasonably-pure drinking water. But even in areas having water suitable for human consumption, such water may contain minerals, e.g., iron and calcium, and/or chemicals and other substances.
While such non-water constituents may not be harmful to humans, they often impart an unpleasant taste or odor to the water. And normally-high-quality drinking water sometimes contains bacteria or other microorganisms which may impart a bad taste to the water or otherwise impair its quality. Often, such an eventuality results from a temporary deficiency in the water treatment facility.
One well-known approach for removing impurities from drinking water is distillation. Distillation involves boiling water to form water vapor and then cooling such vapor to a temperature below the condensation temperature, i.e., below about 212xc2x0 F. The resulting liquid, sometimes referred to as condensate or distillate, is collected for drinking or the like. Distillation separates pure water from the entrained minerals and other potentially bad-tasting impurities. And quite aside from improving the sensory quality of water, the high temperatures involved in the process are sufficient to kill many types of potentially-harmful microorganisms.
Water distillers commonly use a heating coil to boil, as steam, the water from a raw water container. A fan blows air across condensing coils which cools the steam and condenses it back to now-purified water. The distiller electrical circuit usually has some type of thermostat to shut down the distiller when the water in the raw water container is exhausted or is nearly so.
U.S. Pat. Nos. 4,342,623 (Loeffler) and U.S. Pat. No. 4,861,435 (Sweet, Jr.) disclose control circuits for distillers. The circuit of the Loeffler patent uses a single thermostat in series with the incoming electrical line to shut off all functions of the distiller including the fan and heater coil. Such thermostat must be manually reset after tripping.
The apparatus disclosed in the Sweet, Jr. patent carries out what might be described as a continuous, rather than a batch, distilling process. Water is boiled in a boiling tank and transferred, in the form of steam, to a storage tank. When the storage tank is substantially full, a float switch signals that fact by shutting down that part of the apparatus used for distilling. As distilled water is consumed by the user, distilling resumes. And if the rate of consumption is at least equal to the rate of distillation, the distilling process is continuous.
The apparatus electrical circuit (which, in view of the invention, is relatively complex) includes a pressure switch, a float switch, two thermostats and a water solenoid. There is apparently no fan.
An improved water distiller control circuit which addresses problems and shortcomings of known control circuits would be an important advance in the art.
It is an object of the invention to provide an improved control circuit for a water distiller.
Another object of the invention is to provide a distiller control circuit which addresses problems and shortcomings of known control circuits.
Another object of the invention is to provide a distiller control circuit for use in a batch-type distiller.
Yet another object of the invention is to provide a distiller control circuit which thermostatically controls the distiller fan independently of the distiller heater coil.
Another object of the invention is to provide a distiller control circuit which has fewer components that prior art distiller control circuits.
Still another object of the invention is to provide a distiller control circuit which uses temperature parameters rather than liquid level parameters (for example, as sensed by a float switch) for distiller control. How these and other objects are accomplished will become apparent from the following descriptions and from the drawings.
The new distiller control circuit is particularly well suited for a distiller having a condensing platform and a raw water vessel and distillate container mounted on such platform. The circuit includes a power bus comprising first and second lines connected to an electric cord which, during distillation, is plugged into xe2x80x9chotxe2x80x9d and neutral terminals of, e.g., a residential electrical system.
A fan circuit is mounted in and fixed with respect to the condensing platform, is permanently connected across the first and second lines and comprises a fan motor and a fan thermostat in series. Such thermostat is normally open at a first fan thermostat temperature and closes automatically when its temperature is elevated to its xe2x80x9cset point,xe2x80x9d i.e., a second fan thermostat temperature higher than the first fan thermostat temperature. And the fan thermostat is of the type which re-opens automatically when its temperature diminishes to some value incrementally below the set point.
The distiller circuit also has a heater circuit mounted in and fixed with respect to the raw water vessel. During distilling, such heater circuit is connected across the first and second lines and comprises a heater and a heater thermostat in series. The heater thermostat is closed at a first heater thermostat temperature and automatically opens at a second heater thermostat temperature which is higher than the first heater thermostat temperature. But, notably, the heater thermostat is of the manually-reset type and once opened by a rise in temperature at the conclusion of distillation, must be re-closed.
A highly preferred distiller incorporates an innovative arrangement connecting the heater circuit and the fan circuit to one another and for connecting the heater circuit to electrical power assuming the condensing platform is plugged into, e.g., a wall outlet. The heater circuit is mounted in the vessel and terminates in a male connector and the platform has a female connector in electrical contact with the male connector when the vessel is mounted on the platform. The female connector comprises a pair of spaced-apart slots and the male connector comprises a pair of similarly-spaced studs for sliding, electrically-conductive engagement with the slots when the raw water vessel is inserted into the condensing platform.
Another aspect of the invention involves a mechanism for resetting the heater thermostat after such thermostat opens at the conclusion of a distilling cycle. The reset mechanism has a contact surface exposed on the raw water vessel. The distillate container is closely proximate but spaced slightly from such contact surface when the container and the vessel are mounted on the platform.
In a preferred embodiment, the reset mechanism comprises a bar which has a contact surface and a reset surface. The bar is mounted for movement between a first position and a second position, is at the first position which the heater thermostat xe2x80x9ctrips,xe2x80x9d and is urged to the second position when the user depresses the contact surface. When the bar is at the second position, its reset surface urges the heater thermostat to the reset position.
In a specific embodiment, the bar is an L-shaped first class lever having the contact surface and the reset surface spaced from one another. The lever fulcrum is between the contact surface and the reset surface.
Other details of the invention are set forth in the following detailed description and in the drawings.